<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>


<script>
     //发布者--目标
    class Dep{
        constructor() {
            //记录所有的订阅者
            this.subs=[]
        }
        //添加订阅者
        addSub(sub){
            if (sub&&sub.update){
                this.subs.push(sub)
            }
        }
        //发布通知
        notify(){
            this.subs.forEach(sub=>{
                sub.update()
            })
        }

    }

    //订阅者--观察者
    class Watcher{
        update(){
            console.log('update')
        }
    }

    //测试
    let dep=new Dep()
    let watcher=new Watcher()
    dep.addSub(watcher)
    dep.notify()
</script>

</body>
</html>
